It is common practice in geographical areas where the crop is grass seed, to burn the stubble, loose grass, etc. (hereinafter sometimes "grass residue") after harvest to sterilize the soil to lessen substantially the growth of undesirable plant life and spore or insect borne disease during the next growing season. The burning process ladens the air with smoke particles, increasing the pollution thereof dramatically.
I am aware of a number of attempts to lessen the smoke produced during field burning operations. Some of these have operated on the principle of directing an intense flame on the grass residue in the hopes of lessening the production of smoke. Some of these have been partially successful, in that less smoke is produced, but the high temperatures cause rapid deterioration of the equipment and the repair rate is high indeed.